Some of the countries and regions exhibiting remarkable economic growth are in an unstable electricity environment, where power failure and instantaneous voltage drop often occur, because infrastructure development fails to catch up with the scale of its economic growth. In addition, recent large-scale introduction of natural energy may result in an unstable electricity environment even in regions having an already-developed electricity environment.
Meanwhile, in a data center, many IT devices are installed together, and accordingly power consumption and installation area of the devices have been increasing. For this reason, with an increasing demand for the power saving and downsizing of each device, a power supply unit has been requested to achieve improvement in power efficiency and enhancement in power density.
However, one of factors hindering the enhancement in the power density of the power supply unit is the instantaneous voltage drop described above. The instantaneous voltage drop stops power supply for a period of several milliseconds (ms) to several seconds (s). A power supply device is equipped with a compensation capacitor so that the operation of each IT device would not be stopped even in the event of the instantaneous voltage drop. The compensation capacitor accumulates energy in a normal state, and feeds the energy at the occurrence of the instantaneous voltage drop to keep the IT device running.
The above-described techniques are disclosed, for example, in Japanese Laid-open Patent Publications Nos. 2003-79069, 2008-5565, and 2001-178134.
However, in order to meet a request to have high reliability, the power supply device has to have a large-capacity compensation capacitor. Such a large-capacity compensation capacitor occupies a large area for installation inside the power supply device (about 20%, for example), which increases the size of the power supply device.
An aspect of the embodiments aims to provide a power supply control device and a power supply device which enable compensation for long-time instantaneous voltage drop with the downsized power supply device.